This invention relates to a method for conducting an etching process which uses a plasma of a process gas. This etching process is conducted on a wafer W including a substrate 101, an underlying film 102, 103 formed on the substrate, and a film 104 to be etched that is formed on the underlying film. A main etching gas formed up of a chlorine-containing gas and an oxygen-containing gas, and a nitrogen-containing gas are used as the process gas. In this etching method, etching is conducted under a condition that an N2+/N2 intensity ratio of N2+ to N2, derived from emission spectra of the plasma, is at least 0.6.
Legal claims defining the scope of protection, as filed with the USPTO.
1. An etching method comprising the steps of: providing an object including a substrate, an underlying film made of a silicon-containing film formed on the substrate, and a film to be etched that is made of a tungsten-containing film formed on the underlying film; and using a plasma of a process gas to carry out an etching process for the object, wherein: a chlorine-containing gas, an oxygen-containing gas, and a nitrogen-containing gas are used as the process gas to etch the tungsten-containing film under a condition that an N 2 + /N 2 intensity ratio of N 2 + to N 2 , derived from emission spectra of the Plasma, is at least 0.6, the chlorine-containing gas is a Cl 2 gas, the oxygen-containing gas is an O 2 gas, and the nitrogen-containing gas is an N 2 gas, and the silicon-containing film is a polysilicon film, and the tungsten-containing film is a tungsten film of a stacked structure of a tungsten nitride film and a tungsten film.
2. The etching method according to claim 1 , wherein: the plasma is generated by using microwaves.
3. The etching method according to claim 2 , wherein: the plasma is generated by using the microwaves radiated from a planar antenna.
4. The etching method according to claim 3 , wherein: the planar antenna is a radial line slot antenna.
5. The etching method according to claim 1 , wherein: the process gas supplied into a processing vessel is activated to be changed into a plasma by using microwaves radiated from a radial line slot antenna at an electric power of at least 2000 W; and a ratio of a flow rate of the N 2 gas to a flow rate of the Cl 2 gas is at least 200% in the process gas supplied into the processing vessel.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
March 13, 2007
October 30, 2012
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